This invention relates to plastic strand granulation and, more specifically, to an improved rotary helical cutter and method for manufacturing thermoplastic micropellets.
Thermoplastic micropellets are similar to thermoplastic pellets, but are much smaller. Micropellets have a diameter of about 0.020 inches and a length of about 0.020 inches. Thermoplastic micropellets have many uses. For example, micropellets are used as a blasting media.
Thermoplastic pellets are produced by extruding a thermoplastic strand. After cooling, the strand is send to a granulator. Within the granulator, a rotor cuts the thermoplastic strands into pellets.
Granulators for making traditional pellets have been used to make the thermoplastic micropellets. The results have not been entirely satisfactory.
Because traditional thermoplastic pellets are often melted before being formed into a final product, the shape and size of the pellets could vary without cause for concern. Micropellets, on the other hand, are an end product. Because they are often used as a projectile in a machine, the tolerances for the shape of the micropellet are much higher.
The waste from conventional granulators has been very high. To achieve even this modest level of yield, the machines must operate relatively slowly. Such a low yield coupled with a relatively slow operating speed results in increased costs in manufacturing micropellets as well as delays in production.
An improved apparatus and method for manufacturing micropellets at high efficiency and with an increased speed is highly desirable.